U.S. patent number 10,424,809 [Application Number 15/637,076] was granted by the patent office on 2019-09-24 for secondary battery, method for manufacturing same, and battery pack employing same.
This patent grant is currently assigned to SANYO Electric Co., Ltd.. The grantee listed for this patent is Sanyo Electric Co., Ltd.. Invention is credited to Hiroyuki Inoue, Hiroshi Maesono, Yohei Muroya, Shinichirou Yoshida.
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United States Patent |
10,424,809 |
Yoshida , et al. |
September 24, 2019 |
Secondary battery, method for manufacturing same, and battery pack
employing same
Abstract
A secondary battery including an electrode body that includes a
positive electrode plate and a negative electrode plate, an outer
body that houses the electrode body, a metal sealing plate that
seals an opening of the outer body, a positive electrode collector
electrically connected to the positive electrode plate and the
sealing plate, a negative electrode external terminal connected to
the negative electrode plate through a negative electrode
collector. In the secondary battery, a first projection and a
second projection are formed on a surface of the sealing plate on a
battery inner side, the positive electrode collector includes a
first opening and a cut-out, the first projection is disposed in
the first opening, the first projection and an edge portion of the
first opening is welded and connected to each other, and the second
projection is disposed in the cut-out.
Inventors: |
Yoshida; Shinichirou (Hyogo,
JP), Muroya; Yohei (Hyogo, JP), Maesono;
Hiroshi (Hyogo, JP), Inoue; Hiroyuki (Hyogo,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Sanyo Electric Co., Ltd. |
Daito-shi, Osaka |
N/A |
JP |
|
|
Assignee: |
SANYO Electric Co., Ltd.
(Daito-shi, JP)
|
Family
ID: |
61010048 |
Appl.
No.: |
15/637,076 |
Filed: |
June 29, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180034095 A1 |
Feb 1, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Jul 28, 2016 [JP] |
|
|
2016-148098 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M
2/0247 (20130101); H01M 10/05 (20130101); B60L
50/64 (20190201); H01M 4/13 (20130101); H01M
2/266 (20130101); H01M 2/08 (20130101); H01M
4/0404 (20130101); H01M 4/0402 (20130101); H01M
10/052 (20130101); Y02T 10/70 (20130101); Y02T
10/705 (20130101); H01M 2/0245 (20130101); Y02T
10/7005 (20130101); H01M 2/263 (20130101) |
Current International
Class: |
H01M
10/05 (20100101); H01M 2/08 (20060101); H01M
2/26 (20060101); H01M 4/04 (20060101); B60L
50/64 (20190101); H01M 4/13 (20100101); H01M
2/02 (20060101); H01M 10/052 (20100101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2009-87707 |
|
Apr 2009 |
|
JP |
|
2009-87727 |
|
Apr 2009 |
|
JP |
|
2011-18645 |
|
Jan 2011 |
|
JP |
|
Primary Examiner: Cronin; Rena Dye
Attorney, Agent or Firm: Westerman, Hattori, Daniels &
Adrian, LLP
Claims
What is claimed is:
1. A secondary battery comprising: an electrode body that includes
a first electrode plate and a second electrode plate; an outer body
that includes an opening, the outer body housing the electrode
body; a metal sealing plate that seals the opening; a first
electrode collector electrically connected to the first electrode
plate; and a second electrode external terminal electrically
connected to the second electrode plate, the second electrode
external terminal being attached to the sealing plate while in an
insulated state with respect to the sealing plate, wherein the
sealing plate includes a first projection and a second projection
on a surface on a battery inner side, wherein the first electrode
collector includes a first opening, and a second opening or a
cut-out, wherein the first projection is disposed in the first
opening, and the first projection and an edge portion of the first
opening are welded and connected to each other, and wherein the
second projection is disposed in the second opening or the
cut-out.
2. The secondary battery according to claim 1, wherein a recess is
formed in a distal end of the first projection.
3. The secondary battery according to claim 1, wherein a thin wall
portion is formed around the first opening.
4. The secondary battery according to claim 1, wherein a collector
projection that protrudes towards an electrode body side is formed
in the edge portion of the first opening.
5. The secondary battery according to claim 1, wherein, in a
surface of the sealing plate on a battery outer side, a first
recess is formed at a position corresponding to the first
projection, and a second recess is formed at a position
corresponding to the second projection.
6. The secondary battery according to claim 1, wherein a gap is
formed between an end portion of the second projection on a first
projection side, and an edge of the second opening or the
cut-out.
7. The secondary battery according to claim 1, wherein the first
electrode collector includes the cut-out, and the second projection
is disposed in the cut-out.
8. The secondary battery according to claim 1, wherein a tapered
portion is formed in an end portion of the fiust opening on a
sealing plate side.
9. A battery pack comprising: a plurality of the secondary
batteries according to claim 1, wherein between two adjacent
secondary batteries, the negative electrode external terminal of
one secondary battery, and an outer surface of the sealing plate of
the other secondary battery are connected to each other with a bus
bar.
10. The battery pack according to claim 9, wherein in each
secondary battery, the electrode body is fixed to the outer body by
being pressed from both sides by a pair of side walls of the outer
body.
11. A battery pack comprising: a plurality of the secondary
batteries according to claim 5, wherein between two adjacent
secondary batteries, the negative electrode external terminal of
one secondary battery, and an outer surface of the sealing plate of
the other secondary battery are connected to each other with a bus
bar, and wherein the bus bar is welded and connected to the outer
surface of the sealing plate between the first recess and the
second recess.
12. A method for manufacturing a secondary battery that includes an
electrode body that includes a first electrode plate and a second
electrode plate, an outer body that includes an opening, the outer
body housing the electrode body, a metal sealing plate that seals
the opening, a first electrode collector electrically connected to
the first electrode plate, and a second electrode external terminal
electrically connected to the second electrode plate, the second
electrode external terminal being attached to the sealing plate
while in an insulated state with respect to the sealing plate, in
which the sealing plate includes a first projection and a second
projection on a surface on a battery inner side, the first
electrode collector includes a first opening, and a second opening
or a cut-out, the first projection is disposed in the first
opening, and the first projection and an edge portion of the first
opening are welded and connected to each other, and the second
projection is disposed in the second opening or the cut-out, the
method comprising: welding the first projection and the edge
portion of the first opening to each other by projecting an energy
ray.
13. The method for manufacturing a secondary battery according to
claim 12 further including a second electrode collector connected
to the second electrode external terminal and the second electrode
plate, the method further comprising: fixing the first electrode
collector and the second electrode collector to the sealing plate;
bending, after the fixing, the first electrode collector and the
second electrode collector; and welding and connecting, after the
bending, the first electrode collector to the first electrode
plate, and the second electrode collector to the second electrode
plate.
14. The method for manufacturing a secondary battery according to
claim 12, wherein a pair of cut-out portions are formed in the
first electrode collector at a portion where the bending is
performed.
15. The method for manufacturing a secondary battery according to
claim 12, wherein a tapered portion is formed in an end portion of
the first opening on a sealing plate side.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
The present invention application claims priority to Japanese
Patent Application No. 2016-148098 filed in the Japan Patent Office
on Jul. 28, 2016, the entire contents of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
The present disclosure relates to a secondary battery, a method for
manufacturing the same, and a battery pack employing the same.
Description of Related Art
Square secondary batteries such as alkaline secondary batteries and
nonaqueous electrolyte secondary batteries are used in power
sources for driving electric vehicles (EV), hybrid electric
vehicles (HEV, PHEV), and the like.
In such square secondary batteries, a battery case includes a
bottomed cylindrical square outer body including an opening and a
sealing plate that seals the opening. The battery case houses
therein an electrode body including positive electrode plates,
negative electrode plates, and separators, and an electrolyte. A
positive electrode external terminal and a negative electrode
external terminal are attached to the sealing plate with an
insulating member in between. The positive electrode terminal is
electrically connected to the positive electrode plates through a
positive electrode collector, and the negative electrode terminal
is electrically connected to the negative electrode plates through
a negative electrode collector.
Furthermore, as disclosed in Japanese Published Unexamined Patent
Application No. 2011-18645 (Patent Document 1), a secondary battery
has been proposed in which a positive electrode collector is
connected to a surface of the sealing plate on a battery inner
side, and in which the battery case also serves as a positive
electrode terminal. Such a configuration is advantageous in that
the number of components can be reduced.
However, the method for connecting the positive electrode collector
and the sealing plate to each other has not been taken into
consideration in detail.
BRIEF SUMMARY OF THE INVENTION
In secondary batteries employed for, for example, power sources for
driving electric vehicles (EV), hybrid electric vehicles (HEV,
PHEV), and the like, the conductive path from the electrode body to
the outside of the battery is required to have a strong structure
that is not easily broken and damaged even when a strong impact or
a vibration is applied thereto.
An object of the claimed disclosure is to provide a secondary
battery that has higher reliability, a method for manufacturing the
same, and a battery pack that employs the same.
A square secondary battery according to an aspect of the present
disclosure includes an electrode body that includes a first
electrode plate and a second electrode plate, an outer body that
includes an opening, the outer body housing the electrode body, a
metal sealing plate that seals the opening, a first electrode
collector electrically connected to the first electrode plate, and
a second electrode external terminal electrically connected to the
second electrode plate, the second electrode external terminal
being attached to the sealing plate while in an insulated state
with respect to the sealing plate. In the secondary battery, the
sealing plate includes a first projection and a second projection
on a surface on a battery inner side, the first electrode collector
includes a first opening, and a second opening or a cut-out, the
first projection is disposed in the first opening, and the first
projection and an edge portion of the first opening are welded and
connected to each other, and the second projection is disposed in
the second opening or the cut-out.
In the configuration described above, the sealing plate and the
first electrode collector are welded and connected at the first
projection and the first opening, the second projection is disposed
in the second opening or the cut-out. Accordingly, even when force
in a direction that rotates the first electrode collector on a
plane parallel to the sealing plate is applied, a load applied to
the welded connection between the first projection and the first
opening can be suppressed. Accordingly, the connection between the
sealing plate and the first electrode collector can be prevented
from being broken and damaged, and a secondary battery with higher
reliability can be obtained.
Desirably, the recess is formed in a distal end of the first
projection. With the above, a larger welded connection can be
formed between the first projection and the edge portion of the
first opening. Accordingly, the secondary battery becomes more
reliable.
Desirably, a thin wall portion is formed around the first opening.
With the above, the first projection and the edge portion of the
first opening can be welded and connected in a further firm manner
without increasing the height of the first projection, and a
portion of the sealing plate 2 in the vicinity of the first
projection can be prevented from being damaged and broken.
Desirably, a collector projection that protrudes towards an
electrode body side is formed in the edge portion of the first
opening. With the above, a larger welded connection can be formed
between the first projection and the edge portion of the first
opening. Accordingly, the secondary battery becomes more
reliable.
Desirably, in a surface of the sealing plate on a battery outer
side, a first recess is formed at a position corresponding to the
first projection, and a second recess is formed at a position
corresponding to the second projection. With the above, since the
first projection and the second projection are reliably formed into
predetermined shapes, the sealing plate and the collector can be
connected to each other in a further firm manner. Furthermore, when
welding and connecting the first projection and the edge portion of
the first opening to each other, since heat can be suppressed from
being conducted through the sealing plate and from escaping from
the vicinity of the welded portion, the first projection and the
edge portion of the first opening can be welded and connected in a
further firm manner.
Desirably, a gap is formed between an end portion of the second
projection on a first projection side, and an edge of the second
opening or the cut-out. With the above, disposition of the first
projection and the second projection in the first opening provided
in the first collector and the second opening or the cut-out is
facilitated.
Desirably, the first electrode collector includes the cut-out, and
the second projection is disposed in the cut-out. With the above,
disposition of the first projection and the second projection in
the first opening provided in the first collector and the cut-out
is facilitated.
Desirably, a tapered portion is formed in an end portion of the
first opening on a sealing plate side. With the above, disposition
of the first projection in the first opening is facilitated.
A battery pack according to an aspect of the present disclosure
includes a plurality of the secondary batteries described above, in
which between two adjacent secondary batteries, the negative
electrode external terminal of one secondary battery, and an outer
surface of the sealing plate of the other secondary battery are
connected to each other with a bus bar.
In the battery pack described above, desirably, in each secondary
battery, the electrode body is fixed to the outer body by being
pressed from both sides by a pair of side walls of the outer body.
With the above, a load can be reliably prevented from being applied
to the welded connection between the sealing plate and the first
electrode collector when an impact or a vibration is applied to the
secondary battery.
Between two adjacent secondary batteries, desirably, the negative
electrode external terminal of one secondary battery, and an outer
surface of the sealing plate of the other secondary battery are
connected to each other with a bus bar, and the bus bar is,
desirably, welded and connected to the outer surface of the sealing
plate between the first recess and the second recess. With such a
configuration, the sealing plate and the bus bar can be reliably
connected at a predetermined position with the first recess and the
second recess serving as a marker.
A method for manufacturing a square secondary battery according to
an aspect of the present disclosure, the secondary battery
including an electrode body that includes a first electrode plate
and a second electrode plate, an outer body that includes an
opening, the outer body housing the electrode body, a metal sealing
plate that seals the opening, a first electrode collector
electrically connected to the first electrode plate, and a second
electrode external terminal electrically connected to the second
electrode plate, the second electrode external terminal being
attached to the sealing plate while in an insulated state with
respect to the sealing plate, in which the sealing plate includes a
first projection and a second projection on a surface on a battery
inner side, the first electrode collector includes a first opening,
and a second opening or a cut-out, the first projection is disposed
in the first opening, and the first projection and an edge portion
of the first opening are welded and connected to each other, and
the second projection is disposed in the second opening or the
cut-out, the method including welding the first projection and the
edge portion of the first opening to each other by projecting an
energy ray.
In the configuration described above, the sealing plate and the
first electrode collector are welded and connected at the first
projection and the first opening, the second projection is disposed
in the second opening or the cut-out. Accordingly, even when force
in a direction that rotates the first electrode collector on a
plane parallel to the sealing plate is applied, a load applied to
the welded connection between the first projection and the first
opening can be suppressed. Accordingly, the connection between the
sealing plate and the first electrode collector can be prevented
from being broken and damaged, and a secondary battery with higher
reliability can be obtained.
Desirably, the method for manufacturing a secondary battery that
further includes a second electrode collector connected to the
second electrode external terminal and the second electrode plate,
further includes fixing the first electrode collector and the
second electrode collector to the sealing plate, bending, after the
fixing, the first electrode collector and the second electrode
collector, and welding and connecting, after the bending, the first
electrode collector to the first electrode plate, and the second
electrode collector to the second electrode plate.
Desirably, a pair of cut-out portions are formed in the first
electrode collector at a portion where the bending is performed.
With the above, a load applied to the welded connection between the
sealing plate and the first electrode collector can be suppressed
when the first electrode collector is bent.
The present disclosure is capable of providing a secondary battery
that has higher reliability, a method for manufacturing the same,
and a battery pack that employs the same.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a perspective view of a square secondary battery
according to an exemplary embodiment;
FIG. 2 is a cross-sectional view taken along line II-II in FIG.
1;
FIG. 3 is a plan view of an electrode body according to the
exemplary embodiment;
FIG. 4 is a top view of a sealing plate after components have been
attached;
FIG. 5 is a bottom view of the sealing plate after the components
have been attached;
FIG. 6 is an enlarged cross-sectional view of a portion near a
connection between the sealing plate and a positive electrode
collector taken in a longitudinal direction of the sealing
plate;
FIG. 7 is an enlarged bottom view of the portion near the
connection between the sealing plate and the positive electrode
collector;
FIG. 8 is an enlarged cross-sectional view of a first projection
and a first opening before the welded connection is carried
out;
FIG. 9 illustrates enlarged cross-sectional views of the vicinity
of the first projection and the first opening, and illustrates
diagrams depicting the vicinity of the first projection and the
first opening before and after carrying out the welded
connection;
FIG. 10 is a top view of a second projection and a cut-out;
FIG. 11 is a top view of a battery pack;
FIG. 12 is an enlarged view of a vicinity of a second projection
and a second opening of a square secondary battery according to a
first modification; and
FIG. 13 is a top view of a sealing plate according to a second
modification after components have been attached.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a configuration of a square secondary battery 20
according to an exemplary embodiment will be described. Note that
the present disclosure is not limited to the following exemplary
embodiment.
FIG. 1 is a perspective view of the square secondary battery 20.
FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1.
As illustrated in FIGS. 1 and 2, the square secondary battery 20
includes a battery case formed of a square outer body 1 including
an opening, and a sealing plate 2 that seals the opening. The outer
body 1 and the sealing plate 2 are, desirably, formed of metal and
are, desirably, formed of aluminum or an aluminum alloy, for
example. An electrode body 3 in which at least one positive
electrode plate and at least one negative electrode plate are
stacked or wound with at least one separator interposed
therebetween are housed in the outer body 1 together with an
electrolyte. An insulation sheet 14 is disposed between the
electrode body 3 and the outer body 1.
A positive electrode collector 6 is connected to the positive
electrode plate constituting the electrode body 3. The positive
electrode collector 6 is connected to an inner surface of the
sealing plate 2. With the above, the positive electrode plate is
electrically connected to the sealing plate 2 through the positive
electrode collector 6. The positive electrode collector 6 is,
desirably, formed of metal and is, desirably, formed of aluminum or
an aluminum alloy.
A negative electrode collector 7 is connected to the negative
electrode plate constituting the electrode body 3. The negative
electrode collector 7 is connected to a negative electrode external
terminal 8. An inner side insulating member 9 is disposed between
the negative electrode collector 7 and the sealing plate 2. An
external side insulating member 10 is disposed between the negative
electrode external terminal 8 and the sealing plate 2. With the
above, the negative electrode collector 7 and the negative
electrode external terminal 8 are insulated from the sealing plate
2. The negative electrode collector 7 is, desirably, formed of
metal and is, desirably, formed of copper or a copper alloy. The
inner side insulating member 9 and the external side insulating
member 10 are, desirably, formed of resin. The negative electrode
external terminal 8 is, desirably, formed of metal and is,
desirably, formed of copper or a copper alloy. Furthermore,
desirably, the negative electrode external terminal 8 includes a
first metal portion 8a disposed on the inner side of the battery,
and a second metal portion 8b disposed on the external side of the
battery. In such a case, desirably, the first metal portion 8a is
formed of copper or a copper alloy, and the second metal portion is
formed of aluminum or an aluminum alloy. Note that nickel plating
may be applied to the surface of the negative electrode external
terminal 8.
A gas discharge valve 17 that breaks when the pressure inside the
battery case becomes equivalent to or larger than a predetermined
value and that discharges gas inside the battery case to the
outside of the battery case is provided in the sealing plate 2. An
electrolyte injection hole 15 is provided in the sealing plate 2,
and the electrolyte injection hole 15 is sealed with a sealing plug
16 after the electrolyte is injected inside the battery case.
A method for manufacturing the square secondary battery 20 will be
described next.
Fabrication of Positive Electrode Plate
A positive electrode slurry containing
lithium-nickel-cobalt-manganese composite oxide as a positive
electrode active material, polyvinylidene fluoride (PVdF) as a
binding agent, a carbon material as a conductive material, and
N-methylpyrrolidone (NMP) is fabricated. The positive electrode
slurry is coated on both surfaces of a long aluminum foil that is
15 .mu.m thick and that serves as a positive electrode core body.
Subsequently, by drying the above, the N-methylpyrrolidone in the
positive electrode slurry is removed and the positive electrode
active material layers are formed on the positive electrode core
body. Subsequently, after compressing the positive electrode active
material layers to a predetermined thickness, the positive
electrode active material layers are cut into a predetermined
shape. The positive electrode plate obtained in the above manner
includes a positive electrode core body exposed portion 4 in which
no positive electrode active material mixture layers are formed at
an end portion of the long positive electrode core body in the
width direction and in the longitudinal direction on both sides of
the positive electrode core body.
Fabrication of Negative Electrode Plate
A negative electrode slurry containing graphite as a negative
electrode active material, styrene-butadiene rubber (SBR) as a
binding agent, carboxymethyl cellulose (CMC) as a thickener, and
water is fabricated. The negative electrode slurry is coated on
both surfaces of a long copper foil that is 8 .mu.m thick and that
serves as the negative electrode core body. Subsequently, by drying
the above, the water in the negative electrode slurry is removed
and the negative electrode active material layers are formed on the
negative electrode core body. Subsequently, after compressing the
negative electrode active material layers to a predetermined
thickness, the negative electrode active material layers are cut
into a predetermined shape. The negative electrode plate obtained
in the above manner includes a negative electrode core body exposed
portion 5 in which no negative electrode active material mixture
layers are formed at an end portion of the long negative electrode
core body in the width direction and along the longitudinal
direction on both sides of the negative electrode core body.
Fabrication of Electrode Body
The wound electrode body 3 is, with the separator interposed in
between, fabricated by winding the positive electrode plate and the
negative electrode plate fabricated in the above manner. As
illustrated in FIG. 3, the electrode body 3 includes the wound
positive electrode core body exposed portion 4 at a first end
portion of the electrode body 3 in the winding axis direction, and
a wound negative electrode core body exposed portion 5 at a second
end portion. Note that the outermost peripheral of the electrode
body 3 is, desirably, covered by the separator.
Attaching Negative Electrode Collector and Negative Electrode
External Terminal to Sealing Plate
In a vicinity of a terminal attachment hole 2e provided in the
sealing plate 2, the inner side insulating member 9 and a base 7a
of the negative electrode collector 7 are disposed on the battery
inner surface side of the sealing plate 2, and the external side
insulating member 10 is disposed on a battery outer surface side of
the sealing plate 2. Subsequently, the negative electrode external
terminal 8 is inserted through the through holes provided in the
external side insulating member 10, the sealing plate 2, the inner
side insulating member 9, and the base 7a of the negative electrode
collector 7, and a tip of the negative electrode external terminal
8 is riveted on the base 7a of the negative electrode collector 7.
With the above, the negative electrode external terminal 8, the
external side insulating member 10, the inner side insulating
member 9, and the negative electrode collector 7 are fixed to the
sealing plate 2. Note that the riveted portion of the negative
electrode external terminal 8 and the base 7a of the negative
electrode collector 7 are, desirably, further welded and connected
by laser welding and the like such that a welded connection 30 is
formed. A third recess 2f is provided in an outer surface of the
sealing plate 2 and in the vicinity of the terminal attachment hole
2e. The external side insulating member 10 is provided in the third
recess 2f.
As illustrated in FIG. 2, the negative electrode external terminal
8 includes the first metal portion 8a disposed on the inner side of
the battery, and the second metal portion 8b disposed on the
external side of the battery. The first metal portion 8a is
desirably formed of copper or a copper alloy. Desirably, the second
metal portion 8b is formed of aluminum or an aluminum alloy. With
such a configuration, a bus bar formed of aluminum or an aluminum
alloy may be suitably used as a bus bar electrically connecting the
secondary batteries to each other. Note that a nickel layer is
formed on the surface of the first metal portion 8a.
Attaching Positive Electrode Collector to Sealing Plate
As illustrated in FIGS. 6 and 7, a first projection 2a and a second
projection 2b are formed on a surface of the sealing plate 2 on the
battery inner side. Furthermore, a first opening 6x and a cut-out
6y are formed in a base 6a of the positive electrode collector 6.
The first projection 2a of the sealing plate 2 is disposed in the
first opening 6x of the positive electrode collector 6, and the
second projection 2b of the sealing plate 2 is disposed in the
cut-out 6y of the positive electrode collector 6. Furthermore, the
first projection 2a of the sealing plate 2 and an edge portion of
the first opening 6x of the positive electrode collector 6 are
welded to each other by projecting an energy ray such as laser.
With the above, the welded connection 30 is formed. Note that as
illustrated in FIG. 7, desirably, the welded connection 30 is
formed on the entire periphery of the first opening 6x. However,
the welded connection 30 do not necessarily have to be formed on
the entire periphery of the first opening 6x.
Note that a tip of the first projection 2a may be riveted on the
base 6a of the positive electrode collector 6. Furthermore, the
riveted portion may be welded and connected to the base 6a. With
the above, the sealing plate 2 and the positive electrode collector
6 can be connected to each other in a further firm manner.
A distal end recess 2x is formed on a distal end side of the first
projection 2a of the sealing plate 2. With the above, a larger
welded connection 30 can be formed in a reliable manner between the
first projection 2a and the edge portion of the first opening 6x.
Accordingly, the sealing plate 2 and the positive electrode
collector 6 can be connected to each other in a further firm
manner, such that a highly reliable secondary battery is
obtained.
An annular thin wall portion 6c is formed around the first opening
6x of the base 6a of the positive electrode collector 6. Note that
the thin wall portion 6c is formed such that the surface on the
electrode body 3 side of the base 6a of the positive electrode
collector 6 is recessed. Furthermore, a collector projection 6d the
protrudes towards the electrode body 3 side is formed in the edge
portion of the first opening 6x. With the above, an annular groove
is formed on the outside of the collector projection 6d.
Furthermore, the collector projection 6d and the edge portion of
the first opening 6x are welded and connected to each other. With
the above, a larger welded connection 30 can be formed in a
reliable manner between the first projection 2a and the first
opening 6x. Accordingly, the sealing plate 2 and the positive
electrode collector 6 can be connected to each other in a further
firm manner, such that a highly reliable secondary battery is
obtained.
As illustrated in FIG. 6, desirably, a height of the first
projection 2a is smaller than a thickness of the base 6a of the
positive electrode collector 6. With such a configuration, the
sealing plate 2 can be prevented from being broken and damaged in
the vicinity of the first projection 2a.
Desirably, the first projection 2a is provided in the sealing plate
2 by pressing. Furthermore, desirably, a first recess 2c is, in the
sealing plate 2, formed on a back surface side of the first
projection 2a. In such a case, if the height of the first
projection 2a is excessively large, the wall thickness of the
sealing plate 2 in the vicinity of the first projection 2a tends to
become small, and there is a concern that there is a decrease in
the strength in the vicinity of the first projection 2a.
Accordingly, there is a concern that the portion in the vicinity of
the first projection 2a of the sealing plate 2 may become damaged
and broken by a strong impact or vibration. Accordingly, the height
of the first projection 2a is, desirably, smaller than the
thickness of the base 6a of the positive electrode collector 6.
FIG. 8 is an enlarged cross-sectional view of the first projection
2a and the first opening 6x before the welded connection is carried
out. FIG. 9 illustrates enlarged cross-sectional views of the
vicinity of the first projection 2a and the first opening 6x, and
illustrates diagrams depicting the vicinity of the first projection
2a and the first opening 6x before and after carrying out the
welded connection. As illustrated in FIG. 8, desirably, an end
portion of the collector projection 6d on the electrode body 3 side
protrudes more towards the electrode body 3 side than the end
portion of the first projection 2a on the electrode body 3
side.
Desirably, the welded connection 30 is formed by projecting an
energy ray such as laser to the collector projection 6d and the
first projection 2a in a direction indicated by an arrow X in FIGS.
8 and 9. As described above, desirably, the energy ray is projected
to the collector projection 6d in an inclined direction with
respect to a direction perpendicular to the sealing plate 2.
Desirably, the first projection 2a and the edge portion of the
first opening 6x are welded and connected to each other by
projecting a larger dose of energy ray to the collector projection
6d side of the positive electrode collector 6 than to the first
projection 2a of the sealing plate 2 such that the collector
projection 6d side of the positive electrode collector 6 is melted
more than the first projection 2a of the sealing plate 2. With the
above, the first projection 2a and the edge portion of the first
opening 6x can be welded and connected to each other in a further
firm manner.
A tapered portion 6e is formed in an upper end (an end portion on
the sealing plate 2 side) of the first opening 6x provided in the
base 6a of the positive electrode collector 6. With the above, the
first projection 2a can be inserted into the first opening 6x
easily.
As illustrated in FIGS. 5 to 7, the second projection 2b provided
in the sealing plate 2 is disposed inside the cut-out 6y provided
in the base 6a of the positive electrode collector 6. With the
above, a load in a rotational direction on a plane parallel to the
sealing plate 2 can be prevented from being applied to the welded
connection 30 formed between the first projection 2a of the sealing
plate 2 and the edge portion of the first opening 6x provided in
the base 6a of the positive electrode collector 6. With the above,
the welded connection 30 formed between the first projection 2a and
the edge portion of the first opening 6x can be prevented from
being damaged and broken. Accordingly, the secondary battery
becomes more reliable.
The first projection 2a and the second projection 2b of the sealing
plate 2 are disposed so as to be aligned in the longitudinal
direction of the sealing plate 2. As illustrated in FIGS. 7 and 10,
desirably, a gap A is, in the longitudinal direction of the sealing
plate 2, formed between an end portion 2b1 of the second projection
2b on the first projection 2a side and an edge portion of the
cut-out 6y provided in the base 6a of the positive electrode
collector 6. With the above, the welded connection 30 formed
between the first projection 2a and the edge portion of the first
opening 6x can be prevented from being damaged and broken, and the
secondary battery becomes one in which the first projection 2a and
the second projection 2b can be inserted into the first opening 6x
and the cut-out 6y easily.
In the longitudinal direction of the sealing plate 2, desirably,
the distance between the end portion 2b1 of the second projection
2b on the first projection 2a side and the edge portion of the
cut-out 6y provided in the positive electrode collector 6 is
preferably 0.5 mm or more and, more preferably, is 1 mm or more. In
the longitudinal direction of the sealing plate 2, the distance
between the end portion 2b1 of the second projection 2b on the
first projection 2a side and the edge portion of the cut-out 6y
provided in the positive electrode collector 6 is preferably 10 mm
or less and, more preferably, is 5 mm or less.
In the short direction of the sealing plate 2, the distance between
an end portion 2b2 on a first side of the second projection 2b and
the edge portion of the cut-out 6y provided in the positive
electrode collector 6 is preferably smaller than 0.5 mm, more
preferably is 0.3 mm or smaller, and most preferably is 0.1 mm or
smaller. In the short direction of the sealing plate 2, the
distance between an end portion 2b3 of the second projection 2b on
a second side and the edge portion of the cut-out 6y provided in
the positive electrode collector 6 is preferably smaller than 0.5
mm, more preferably is 0.3 mm or smaller, and most preferably is
0.1 mm or smaller. Note that the end portion 2b2 on the first side
of the second projection 2b and the end portion 2b3 on the second
side are, desirably, in contact with the cut-out 6y provided in the
positive electrode collector 6.
The second projection 2b of the sealing plate 2 can be welded and
connected to the edge portion of the cut-out 6y provided in the
base 6a of the positive electrode collector 6.
As illustrated in FIGS. 4 and 5, desirably, the first recess 2c is
formed in the outer surface of the sealing plate 2 at a position
opposing the first projection 2a. Desirably, a second recess 2d is
formed in the outer surface of the sealing plate 2 at a position
opposing the second projection 2b. Furthermore, desirably, a first
end of the bus bar that electrically connects two adjacent square
secondary batteries 20 to each other is connected to a negative
electrode external terminal 8 of one of the square secondary
battery 20, and a second end of the bus bar is welded and connected
to a portion between the first recess 2c and the second recess 2d
of the sealing plate 2 of the other square secondary battery 20.
With such a configuration, the bus bar can be reliably connected to
a predetermined position in a surface of the sealing plate 2 on the
battery outer side.
A pair of first grooves 2g and a pair of second grooves 2h are
formed on the surface of the sealing plate 2 on the battery outer
side. The first grooves 2g are provided in the vicinity of the end
portions of the sealing plate 2 in the short direction so as to
extend in the longitudinal direction of the sealing plate 2. The
electrolyte injection hole 15 and the gas discharge valve 17 are
provided between the pair of first grooves 2g. The second grooves
2h are provided in the vicinity of the end portions of the sealing
plate 2 in the longitudinal direction so as to extend in the short
direction of the sealing plate 2. The two ends of each of the
second grooves 2h are bent such that the groove extend in the
longitudinal direction of the sealing plate 2.
In the longitudinal direction of the sealing plate 2, the first
recess 2c and the second recess 2d are formed between the first
grooves 2g and the second grooves 2h. A line that extends in the
short direction of the sealing plate 2 and that passes through the
center of the first recess 2c does not intersect the first grooves
2g nor the second grooves 2h. A line that extends in the short
direction of the sealing plate 2 and that passes through the center
of the second recess 2d does not intersect the first grooves 2g nor
the second grooves 2h.
Bending of Positive Electrode Collector and Negative Electrode
Collector
As illustrated in FIG. 5, the positive electrode collector 6 and
the negative electrode collector 7 are desirably tabular when
attached to the sealing plate 2. The positive electrode collector 6
attached to the sealing plate 2 is bent at a boundary between the
base 6a and a lead portion 6b. With the above, the positive
electrode collector 6 is formed into a shape in which the lead
portion 6b is bent at an end portion of the base 6a in the short
direction of the sealing plate 2. Furthermore, the negative
electrode collector 7 attached to the sealing plate 2 is bent at
the boundary between the base 7a and a lead portion 7b. With the
above, the negative electrode collector 7 is formed into a shape in
which the lead portion 7b is bent at an end portion of the base 7a
in the short direction of the sealing plate 2. Note that in the
positive electrode collector 6, a pair of cut-out portions 6f and
6g are formed on the two ends of the boundary between the base 6a
and the lead portion 6b. With the above, a load applied to the
welded connection 30 between the sealing plate 2 and the positive
electrode collector 6 can be suppressed when the positive electrode
collector 6 is bent. Furthermore, when the positive electrode
collector 6 is bent, desirably, the positive electrode collector 6
is bent while the base 6a of the positive electrode collector 6 is
pressed towards the sealing plate 2. With the above, a load can be
prevented from being applied to the welded connection 30 formed
between the first projection 2a of the sealing plate 2 and the edge
portion of the first opening 6x of the positive electrode collector
6.
Connecting Positive Electrode Collector and Negative Electrode
Collector to Electrode Body
The lead portion 6b of the positive electrode collector 6 is welded
and connected to the outermost surface of the positive electrode
core body exposed portion 4 wound around the electrode body 3. The
lead portion 7b of the negative electrode collector 7 is welded and
connected to the outermost surface of the negative electrode core
body exposed portion 5 wound around the electrode body 3. Note that
the joining method may include resistance welding, ultrasonic
welding, laser welding, for example.
Assembling Secondary Battery
The electrode body 3 connected to the sealing plate 2 through the
positive electrode collector 6 and the negative electrode collector
7 is covered therearound with the insulation sheet 14.
Subsequently, the electrode body 3 covered with the insulation
sheet 14 is inserted into the outer body 1. Furthermore, an opening
of the outer body 1 is sealed with the sealing plate 2 by laser
welding the outer body 1 and the sealing plate 2. Subsequently, a
nonaqueous electrolyte containing a nonaqueous solvent and
electrolyte salt is injected into the electrolyte injection hole 15
provided in the sealing plate 2, and the electrolyte injection hole
15 is sealed with the sealing plug 16. Desirably, a blind rivet is
used for the sealing plug 16. Note that a metal sealing plug 16 can
be welded and connected to the sealing plate 2.
Battery Pack
FIG. 11 is a top view of a battery pack 70 employing a plurality of
square secondary batteries 20. A plurality of square secondary
batteries 20 are stacked between a pair of metal end plates 71.
Intercell spacers 74 formed of resin are each disposed between the
square secondary batteries 20. The pairs of end plates 71 are
connected to each other with a pair of metal bind bars 72. Note
that the bind bars 72 are fixed to the end plates 71 with securing
members 75. Desirably, the securing members 75 are bolts, rivets,
or the like. Note that the bind bars 72 can be welded and connected
to the end plates 71 without using the securing members 75.
In the square secondary batteries 20 that are adjacent to each
other, the negative electrode external terminal 8 of one of the
square secondary battery 20, and the outer surface of the sealing
plate 2 of the other square secondary battery 20 are connected to
each other through a metal bus bar 73. Note that, desirably, the
bus bar 73 is formed of aluminum or an aluminum alloy. The bus bar
73 is, desirably, welded and connected to the outer surface of the
sealing plate 2 between the first recess 2c and the second recess
2d. With such a configuration, the sealing plate 2 and the bus bar
73 can be reliably connected at a predetermined position with the
first recess 2c and the second recess 2d serving as a marker.
The bus bar 73 includes a bus bar opening 73a. Furthermore, a bus
bar thin wall portion 73b is formed around the bus bar opening 73a.
Furthermore, an edge portion of the bus bar opening 73a is welded
to the sealing plate 2 by laser welding or the like such that a
welded connection 73c is formed.
In the battery pack 70, desirably, the electrode body 3 of each
square secondary battery 20 is fixed to the outer body 1 by being
pressed from both sides with the pair of side walls (the side walls
on the large area side) of the corresponding outer body 1. With the
above, a load can be reliably prevented from being applied to the
welded connection 30 between the sealing plate 2 and the positive
electrode collector 6 when an impact or a vibration is applied to
the square secondary battery 20.
First Modification
In the exemplary embodiment described above, an example is given in
which the cut-out 6y is provided in the base 6a of the positive
electrode collector 6, and the second projection 2b of the sealing
plate 2 is disposed in the cut-out 6y. Instead of providing the
cut-out in the positive electrode collector, a second opening may
be provided and the second projection of the sealing plate may be
disposed in the second opening.
FIG. 12 is an enlarged view of the vicinity of the second
projection and a second opening of the square secondary battery
according to a first modification. As illustrated in FIG. 12, a
second opening 106y is provided in a base 106a of the positive
electrode collector. Note that in such a case as well, in the
longitudinal direction of the sealing plate 2, the gap A is,
desirably, formed between an end portion of the second projection
2b on the first projection side (the right side in FIG. 12) and the
edge portion of the second opening 106y. Furthermore, in the
longitudinal direction of the sealing plate 2, a gap B is,
desirably, formed between an end portion of the second projection
2b on a side (the left side in FIG. 12) opposite to the first
projection side and the edge portion of the second opening
106y.
Second Modification
FIG. 13 is a top view of a square secondary battery according to a
modification and is a diagram corresponding to FIG. 4. In the
square secondary battery according to the second modification,
shapes of grooves formed in the outer surface of the sealing plate
2 are different from those of the square secondary battery 20
described above. As illustrated in FIG. 13, in the square secondary
battery according to the second modification, a third groove 2i and
a fourth groove 2k are provided in the outer surface of the sealing
plate 2.
Furthermore, in the longitudinal direction of the sealing plate 2,
the negative electrode external terminal 8 is disposed between the
third groove 2i and the fourth groove 2k.
The fourth groove 2k includes a groove first area 2k1 that extends
in the short direction of the sealing plate 2, groove second area
2k2 that extends in the longitudinal direction of the sealing plate
2 from a first end portion of the groove first area 2k1, and a
groove third area 2k3 that extends in the longitudinal direction of
the sealing plate 2 from a second end portion of the groove first
area 2k1.
As described above, by having the grooves formed in the vicinity of
the outer peripheral edge throughout substantially the entire
periphery of the outer surface of the sealing plate 2, the sealing
plate 2 and the outer body 1 can be welded and connected in a
further firm manner.
Note that in the battery pack including the plurality of secondary
batteries, desirably, the position where the welded connection
between the sealing plate 2 and the bus bar is formed is between
the first recess 2c and the second recess 2d in the longitudinal
direction of the sealing plate 2, and is between the two grooves in
the short direction of the sealing plate 2. With the above, when
welding and connecting the bus bar to the outer surface of the
sealing plate 2, heat can be suppressed from escaping through the
sealing plate 2, and the bus bar and the sealing plate 2 can be
welded and connected to each other in a further reliable and firm
manner.
(Others)
In the exemplary embodiment described above, an example in which
the positive electrode collector is connected to the sealing plate
has been described; however, the negative electrode collector can
be connected to the sealing plate 2. In such a case, a positive
electrode external terminal is used, and the positive electrode
external terminal, the positive electrode collector, and the
sealing plate are insulated with an insulating member.
The positive electrode external terminal can be connected to the
other side (the outer surface side) of a portion on a surface of
the sealing plate on the battery inner side to where the positive
electrode collector is connected.
The configuration of the electrode body 3 is not particularly
limited to the above configuration. The electrode body 3 may be a
wound electrode body or may be a stacked electrode body.
The positive electrode plate, the negative electrode plate, the
separator, the electrolyte, and the like may have known
configurations.
While detailed embodiments have been used to illustrate the present
invention, to those skilled in the art, however, it will be
apparent from the foregoing disclosure that various changes and
modifications can be made therein without departing from the spirit
and scope of the invention. Furthermore, the foregoing description
of the embodiments according to the present invention is provided
for illustration only, and is not intended to limit the
invention.
* * * * *